Sense of smell detects COVID-19

Along with fever, cough and shortness of breath, many COVID-19 patients report a temporary loss of sense of smell.

It appears that olfactory loss is significantly greater in coronavirus patients compared to the loss often experienced during a cold and, less commonly, in influenza (non-COVID-19) patients.

In some countries, such as France, a patient who claims to have a sudden onset of olfactory loss will be diagnosed as a coronavirus patient – without even being tested. A similar approach is being considered in the UK.

Based on this data, Weizmann Institute of Science investigators developed SmellTracker – an online platform that enables self-monitoring of one’s sense of smell – in order to detect early signs of COVID-19.

Professor Noam Sobel’s laboratory in the Weizmann Institute’s Department of Neurobiology specialises in olfactory research.

The researchers previously developed a mathematical model that accurately characterises a person’s unique sense of smell – a kind of individual ‘olfactory fingerprint’.

SmellTracker, based on this algorithm, is an online test that guides users on how to map their sense of smell using five scents found in every home (spices, vinegar, toothpaste, various scent extracts, peanut butter, etc.).

The smell test takes about five minutes and is able to monitor sudden changes in odour perception that may be an early indication of COVID-19 onset.

The researchers report that the new tool has already successfully identified potential coronavirus cases, which were later confirmed.

Aside from personal monitoring, the test will be beneficial because, as more data is collected, the researchers are more likely to be able to characterise a unique olfactory fingerprint for the early detection of COVID-19.

Eight strains of coronavirus
Olfactory loss was not commonly reported in the city of Wuhan, China, where the first coronavirus outbreak took hold. Nevertheless, preliminary studies conducted in several countries, including Israel and Iran, show that this symptom appears in about 60 per cent of patients.

Scientists estimate that there are currently eight active strains of the virus, and Prof. Sobel’s lab believes that olfactory loss may be a differentiating symptom of the various strains. If this turns out to be true, the SmellTracker will be able to map the various outbreaks geographically.

Are you worried you might have an asymptomatic case of the coronavirus? Will you be testing your sense of smell in future?

For the latest advice, information and resources, go to, or call the 24-hour National Coronavirus Helpline on 1800 020 080. It operates 24 hours a day, seven days a week. If you require translating or interpreting services, call 131 450. Details of your state or territory public health agency are available at

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